Chromatography apparatus and method

ABSTRACT

Sample preparation device for receiving in sealing relation one or more filter assemblies and one or more sample containers, each container uniquely positioned within the device to receive filtered sample from a designated filter. The device includes a body, a lid disposed on the body, a container tray, a base, an integrated seal on the body, a valve and a valve actuator. The tray can be disposed in a vacuum chamber defined by the lid and the body, and one or more sample containers can be disposed in the tray. When properly positioned in the tray in the vacuum chamber, each container is in fluid communication with a single respective filter assembly disposed in sealing relation in a respective aperture in the lid. A single actuation of a valve to place the vacuum chamber under vacuum causes the lid to seal to the base and drives the simultaneous filtration of a plurality of samples.

This application is a divisional of U.S. patent application Ser. No.13/311,597 filed Dec. 6, 2011, which claims priority of U.S. ProvisionalApplication Ser. No. 61/426,849 filed Dec. 23, 2010, the disclosures ofwhich are incorporated herein by reference.

BACKGROUND

To satisfy researchers' demands for more information about theircompounds of interest, manufacturers of HPLC, UHPLC, LC/MS and GC/MSsystems are constantly developing new technologies that lower thedetection limits of these separation systems. Accompanying these everdecreasing detection limits is the need for higher purity samples andcleaner mobile phases. Samples and buffers, after proper filtration, notonly generate higher quality, more consistent results, they alsoincrease instrument uptime and prolong column life.

One conventional sample preparation device for chromatographyapplications is a Millex® filter, commercially available from MilliporeCorporation. These filters are non-sterile, low-extractable filters forclarification or fine particulate removal prior to instrument analysis.Millex® filter units contain a membrane in a housing, such as a highdensity polyethylene or polypropylene housing. One or more filter layersare permanently sealed between two plastic filter holder halves, thefirst half having an inlet port and the second half having an outletport. The outer peripheral edge of the membrane is trapped between thetwo halves. The outer peripheral edges and of the two halves can besealed together by an overmold of plastic to form a liquid tightlysealed device. A variety of membranes and housings ensure chemicalcompatibility with a range of samples and solvents. For example,Millex®-LCR filters contain a hydrophilic PTFE membrane and areHPLC-certified for low levels of UV-absorbing extractables, and providea very clean sample for HPLC analysis. Durapore® (PVDF) filters combinefast flow with low protein binding. Nylon filters provide broad chemicalcompatibility for use with aqueous and organic solutions. MilliporeExpress® PLUS (PES) filters have high flow rates and higher throughput.MF-Millipore™ mixed cellulose ester (MCE) membrane is a widely used,general purpose filter. Glass fiber can be used for clarifying aqueousor organic solutions with high particulate levels and can also bepresent in the housing as a prefilter. Depending on process volume,filter sizes range from 4 mm to 33 mm in diameter. The Millex® filtersare used in conjunction with pressure driven hand-held syringes.

It would be desirable to increase the speed and ease the preparation ofone or more samples for applications such as HPLC analysis, whilereducing the occurrence of human error, the repetitive motion andduration of the applied load necessary to operate hand-held devices, andthe presence of contaminants.

SUMMARY

The embodiments disclosed herein provide an alternative totime-consuming one-at-a-time syringe filters. A driving force such asvacuum is used to drive filtration and process a single sample, ormultiple samples simultaneously and in parallel. In certain embodiments,one or a plurality of disposable filters, each having an integratedfunnel and seal, is used in conjunction with a manifold, to filter oneor a plurality of samples into respective sample containers such asvials that are in liquid-receiving communication with a respectivefilter. In certain embodiments, the disposable filter is packaged ingroups of four, which can be selectively separated from each other. Thefilter assembly design achieves a hold up volume of less than 100 μl. Asa result, smaller starting sample volumes can be used than is the casewith syringes.

In accordance with certain embodiments, a sample preparation devicecomprises a device body, wherein the device is adapted to receive insealing relation one or more filter assemblies. The device is alsoadapted to receive one or more sample containers such as vials. Eachvial is uniquely positioned within the device to receive filtered samplefrom a designated filter. In certain embodiments, the device includes abody, including a base, a removable clear lid disposed on said base insealing relation, a removable vial tray, an integrated seal on the base,a valve and a valve actuator. The removable vial tray can be disposed ina vacuum chamber defined by the lid and the base, and one or more vialscan be removably disposed in the vial tray. When properly positioned inthe vial tray in the vacuum chamber, each vial is in fluid communicationwith a single respective filter assembly disposed in sealing relation ina respective aperture in the lid. In certain embodiments, the assemblyhas an interior region that is in fluid communication with a vacuumsource. Application of vacuum from the vacuum source causes the lid toseal to the base, and drives filtration. A single actuation of a valveto place the vacuum chamber under vacuum causes the simultaneousfiltration of a sample or a plurality of samples.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top perspective view of a filter assembly in accordance withcertain embodiments;

FIG. 2 is a side view of the filter assembly of FIG. 1;

FIG. 3 is a bottom view of the filter assembly of FIG. 1;

FIG. 4 is a top view of the upper housing unit of the filter assembly ofFIG. 1;

FIG. 5 is a bottom perspective view of the filter assembly of FIG. 1;

FIG. 6 is a cross-sectional view of the filter assembly of FIG. 1;

FIG. 7 is a perspective view of a plurality of interconnected filterassemblies in accordance with certain embodiments;

FIG. 8 is a side view of the plurality of filter assemblies of FIG. 7;

FIG. 9 is a perspective view of a sample preparation device with filtersin accordance with certain embodiments;

FIG. 10 is a top view of the device of FIG. 9 (without filters inplace);

FIG. 11 is an exploded view of the device in accordance with certainembodiments;

FIG. 12 is an end view, in cross-section, of the device in accordancewith certain embodiments;

FIG. 13 is an end view, in cross-section, of the device including afilter assembly and vial shown in place, accordance with certainembodiments;

FIG. 14 is a top view of a sample preparation device with filterassemblies in place in accordance with certain embodiments;

FIG. 15 is a top view of membrane support features in the bottom housingof the filter in accordance with certain embodiments;

FIG. 16 is a top view of a connecting member in accordance with certainembodiments;

FIG. 17 is a perspective view of a container tray shown supporting aplurality of containers, in accordance with certain embodiments;

FIG. 18 is top view of a container tray in accordance with certainembodiments;

FIG. 19 is a bottom view of the container tray of FIG. 18;

FIG. 20 is a bottom view of lid in accordance with certain embodiments;

FIG. 21 is a top view of the waste collection tray in accordance withcertain embodiments;

FIG. 22 is a perspective view of the waste collection tray;

FIG. 23 is a perspective view of a sample preparation device including awaste collection tray in accordance with certain embodiments;

FIG. 24 is a perspective view of a valve assembly for placing a vacuumchamber in and out of fluid communication with a vacuum source, inaccordance with certain embodiments;

FIG. 25 is a cross-sectional view of a valve in a sample preparationdevice in accordance with certain embodiments;

FIG. 26 is a partial cross-sectional view of the valve assembly of FIG.24 in accordance with certain embodiments; and

FIG. 27 is a bottom perspective view of the valve assembly of FIG. 24 inaccordance with certain embodiments.

DETAILED DESCRIPTION

Turning to FIGS. 1-6, there is shown a filter assembly 10 particularlysuited for use with the sample preparation device in accordance withcertain embodiments disclosed herein. The filter assembly 10 includes asample reservoir 12. The reservoir 12 is of sufficient volume to hold atypical sample desired to be processed. Suitable sample reservoir 12volumes include 0.5-2.0 ml, although other reservoir volumes are withinthe scope of the embodiments disclosed herein. In accordance withcertain embodiments, the sample reservoir 12 is defined by a fluidimpervious wall 13, which is preferably funnel-shaped such that ittapers inwardly from the open inlet towards the filter compartment withwhich it is in fluid communication via aperture 11. In certainembodiments, the aperture 11 is clover-shaped as best seen in FIG. 4.The funnel-shaped reservoir facilitates filling the reservoir withsample and minimizes the possibility of sample loss during filling.Although a funnel-shape is preferred, other shapes such as cylindricaland cubical, are within the scope of the embodiments disclosed herein.In accordance with certain embodiments, the sample reservoir 12 includesan integrally mounted base 14, the reservoir 12 and base 14 togetherforming a unitary structure and defining an upper housing unit 50 thatcan be formed by injection molding. The base is preferably disk-shaped,and optionally can include a raised dome 15 smaller in diameter than thebase 14 and defining a prefilter chamber 16 (FIG. 6). Preferably theupper housing unit 50 is made from an inexpensive plastic material sothat it can be disposable after a single use, and is made from amaterial that is injection moldable. A preferred material is highdensity polyethylene with 1-3% titanium dioxide.

The upper housing unit 50 is mounted to a lower housing unit 60, whichalso can be formed by injection molding. Heat sealing such as byultrasonic welding can be used to affix the upper and lower unitstogether. To that end, the underside of the base 14 can have concentricraised annular rings 18 and 19 (FIG. 4) which receive between them araised annular ring 22 (FIG. 6) in the lower housing unit 60, creating astrong bond upon the application of heat. Lower housing unit 60 includesa membrane support member 17. Preferably the membrane support member 17is made from an inexpensive plastic material so that it can bedisposable after a single use, and is made from a material that isinjection moldable, such as polyolefins, particularly polyethylene. Apreferred material is high density polyethylene, as it exhibits its lowextractables and laser print graphics can be used with it. As seen inFIG. 15, the membrane support member 17 includes one or more openings,such as a plurality of concentric circumferential slits 72, which forman underdrain and allow fluid communication between the inlet of thesample chamber 12 and the outlet 20. A plurality of spokes 73,preferably equally spaced, traverse the slits 72 and help support themembrane. An annular heat seal bead 74 can be provided to seal themembrane to the support. An annular ultrasonic weld energy director 71also can be provided for welding the support to the upper housing unit.The support member 17 is preferably disk-shaped and corresponds in sizeto the upper housing unit base 14. Lower housing unit 60 includes anaxially extending collar member 30 positioned radially inwardly from theouter circumference of the support member 17. The collar member 30 ispreferably overmolded on the support member 17, and is made of athermoplastic elastomer, such as Teknor Apex Monprene® MP 2551B. Thecollar member 30 is configured to engage with an aperture in the samplepreparation device in sealing relation, thereby sealing the filterassembly 10 to the manifold. Preferably the collar member 30 is anannular ring, best seen in FIGS. 5 and 6, having a center along theaxial centerline of the membrane support member 17. Also extendingaxially from the membrane support member 17 is an elongated tip 35,preferably along the axial centerline of the membrane support member 17.The elongated tip 35 includes a bore 36 in fluid communication with thevolume 40 defined between base 14 and support member 17 when the upperand lower housing units are in the assembled condition, as shown in FIG.6. The bore, which is preferably centrally located in the elongated tip35, terminates in outlet 20. It is preferably of sufficient length thatit penetrates into a container 70 (e.g., a standard HPLC vial)positioned in the vacuum chamber operation of the device, as best seenin FIG. 13.

Porous media such as a membrane 38 (FIG. 6) is positioned on themembrane support member 17 and is sealed thereto, such as with the aidof the heat seal bead 74, so that all fluid flow from the inlet 12through the outlet 20 proceeds through the membrane 38 and does notbypass the same. The characteristics of the membrane will depend uponthe sample being processed. Suitable membranes include 0.2 μm PTFEmembranes and 0.45 μm hydrophilized PTFE membranes. Where a prefilter isdesired, it can be positioned in chamber 16 and may include any suitableprefilter for the application, such as one or more layers of glassfiber.

Each filter assembly 10 containing just the membrane has a sample holdup volume of about 100 μl, whereas conventional syringe filter devicescontaining the same type of membrane have a hold up volume of about300-400 μl. Similarly, each filter assembly 10 containing a membrane anda prefilter have a sample hold up volume of about 300 μl, whereasconventional syringe filter devices containing the same combination ofmembrane and prefilter have a sample hold up volume of about 900-1000μl. The benefit of low hold up volume for down-stream HPLC applicationsis that lower sample volume can be used while still obtaining enoughsample for HPLC analysis. With low sample hold up, less sample is lostto the filter, thereby allowing researchers to use their sample for moretests following filtration.

In certain embodiments, a plurality of filter assemblies 10 can beprovided in integrated form. For example, an array of filter assemblies10, such as four-member array shown in FIGS. 7 and 8, can be removablyattached or conjoined in a linear array for ease of handling and use. Incertain embodiments, a connecting member 160 (FIG. 16) is secured toeach of the filter assemblies 10 in the array. For example, theconnecting member 160 can include a plurality of annular rings 61 a-61n. each having the same outside diameter as a base 14 and support memberof a filter assembly 10, and can be positioned between the base 14 andsupport member 17 prior to affixing the base and support membertogether. One or both of the base 14 and support member 17 can includeradially inward raised annular rings which help position the connectingmember 160. Each adjacent annular ring can be removably affixed to thenext annular ring, such as with perforations 62, so that flexing and/ortearing and/or snapping of the same repeatedly will cause the annularrings to separate from one another to disengage the interconnectedarray.

Turning now to FIG. 9, there is shown a body 100 that in cooperationwith filter assemblies 10, functions as a sample preparation device 100.The body 100 includes a base 102 having an elongated support member 105for aligning and supporting a tray 110 for holding a sample containersuch as a vial. The support member 105 includes one or more apertures influid communication with a vacuum source via chamber 104. Preferably thebase 102 is made of a plastic such as polypropylene, with an integratedseal member 120 made of a thermoplastic elastomer. The seal utilizes a“bead” feature to localize contact with the manifold lid around theperimeter of the vacuum manifold. This bead allows force applied by theuser or resulting from a pressure differential to more effectivelycompress the seal and ensure conformity to the lid. Furthermore, theshape of the seal overall with its easily distinguishable left and rightends and arch shape helps to ensure correct placement of the lid uponthe seal; the seal is thus “keyed” so that the lid can only be placed onthe seal in one configuration. Preferably the seal is overmolded to thebase, the bead being integral to the overmold. In accordance withcertain embodiments, the material used for the seal should besufficiently soft, such as a material having a Shore A durometerhardness of 25. Suitable materials include thermoplastic elastomers,with Teknor Apex Monprene® being particularly preferred in view of itschemical resistance properties. The seal should be sufficiently wide toensure contact with the edge of the lid being sealed, but not too wideso as to force the seal to compress over a wide area. Widths of about ⅛inch are suitable.

One or more alignment tabs 106, 107 can be positioned on the top surfaceof the elongated support member 105, the tab or tabs cooperating with acorresponding number of recesses in the vial tray 110 to properly alignand position the vial tray on the body 100.

In certain embodiments, the vial tray 110 is defined by an elongatedbase 111 and angled opposite side walls 113, 114. Preferably the angleof the side wall 113 matches the angle of wall 109 of the body 100. Thevial tray includes a plurality of container receiving apertures 125a-125 n (eight shown), creating vial receiving sockets. As seen in FIGS.17 and 18, in certain embodiments the apertures are configured toreceive and hold standard 12×32 mm vials, and are preferably angled. Theangle is preferably such that the user has visibility of fluid flowinginto the vials during filtration, and such that the fluid flows down theside wall of the vial to minimize or eliminate the trapping of airbubbles, and foaming, during vial filling. The angle ensures that thevials are located at a suitable location relative to the filter tip. Theangle also facilitates access of the vials to the user, enabling theuser to grasp each vial with their fingers while the vial remains in thetray, and attach or remove a vial cap (such as by screwing the cap ontothe vial or off of the vial) while the vial remains in the tray. Thus,the shape of the vial receiving sockets uses this angle to rest eachvial on deep and tall geometry behind the vial, with a minimum heightwrapping around the front. The support, coupled with this “lean-back”angle, is sufficient to prevent loss of vials from all but the mostextreme tipping of the tray, but does not interfere with viewability oraccess to the vials. One suitable angle is about 20° off of vertical.Each aperture can be numbered or otherwise marked to identify eachindividual container supported therein. The vial tray 110 is readilyremovable from the vacuum chamber, and thus can be used as a storagetray for the vials separately from the sample preparation device. Spacedstacking feet 79 may be provided on the underside of the tray 110 asshown in FIG. 19.

As seen in FIGS. 11 and 14, the sample preparation device 100 alsoincludes a removable lid 150. In certain embodiments, the transversecross-sectional shape of the lid 150 is parabolic, matching the shape ofthe perimeter of wall 109 and the seal member 120 along wall 109.Preferably the wall 109 and seal thereon are recessed downwardly fromthe top wall 270 of the chamber 104 (FIG. 11), providing a shoulder forreceiving the edge of the lid 150. Accordingly, lid 150 fits over theseal member 120 along the inner perimeter (FIG. 20) of the parabolicside wall 151, and along the underside 152 of the elongated base portion152. Upon the application of vacuum, the lid 150 thus seals to themember 105 along the lid perimeter, thereby defining a vacuum chamberbetween the lid and the base. Preferably the lid 150 is made of a clearor transparent material, such as a polymethylpentene, which ischemically resistant and allows the user to observe the filtrationprocess as it proceeds, and obtain visual feedback that filtration iscomplete and that sample properly transferred into the vial, forexample.

The lid 150 includes an elongated recessed top surface 145 (FIG. 10),which includes at least one, preferably a plurality, of spaced apertures146 a-146 n. The apertures 146 a-146 n are each configured to receive insealing relation a collar member 30 of a respective filter assembly 10.Accordingly, where a plurality of apertures are present, the apertures146 a-146 n are spaced a sufficient distance from each other toaccommodate a filter assembly 10 sealingly arranged in each. Four suchfilter assemblies 10 are shown so arranged in FIG. 9. Each aperture inthe lid 150 also may be associated with a corresponding sealing member,such as an individual plug that can be removable, or more preferably adoor 147 a-147 n. each of which is preferably pivotable on the lid 150between a closed position (e.g., door 147 e in FIG. 9) in which it sealsagainst its respective aperture, and an open position (e.g., door 147 ain FIG. 9) in which the respective aperture is accessible for sealingengagement with a filter assembly 10. The underside of each doorpreferably includes a raised annular ring 148 that sealingly engages inor about the perimeter of its corresponding aperture on the lid 150 whenthe door is in the closed position. Each door allows the aperture it isassociated with to be sealed in the event that aperture is not beingused to filter a sample. This allows the device to be used to filter anynumber of samples simultaneously, depending upon the number of aperturespresent (eight in the embodiment illustrated).

The body 100 includes chamber 104 which houses a valve for turning thevacuum on or off. For example, as seen in FIGS. 24-27, a ball valve 155(e.g., a two-way, right angle ball valve) is housed in valve cradle 144in the chamber 104. The ball valve can be actuated (e.g., by pivotinghandle 260) between an open position, in which fluid communication witha vacuum source via connector 133 is realized, and a closed position inwhich fluid communication with a vacuum source is shut off.Alternatively, the valve can be controlled by other means known to thoseskilled in the art, such as electrically or pneumatically. The chamber104 is connectible to a vacuum source via integrated connector 133,which provides fluid communication via a hose or the like (not shown),between the chamber 104 and the vacuum source, and thus pulls a vacuum,via the one or more apertures in member 105, in the vacuum chamberregion below the lid 150. For example, tubing 148 is connected, throughthe valve 155, to the vacuum source. A T-fitting 149 is provided in thetubing line, which provides an orifice 141 communicating with the vacuumchamber. The opposite end of the tubing 148 from the connection to thevalve 155 is connected to an orifice fitting 143 to vent.

Turning now to FIGS. 20-23, a waste collection tray 170 can be providedand used in place of the vial tray 110 if filtration to waste isdesired. The waste collection tray 170 can have a plurality of wells 171a-171 n (eight shown), with each well being aligned with a respectiveaperture 146 when the waste collection tray 170 is positioned in thevacuum chamber as per FIG. 23.

In operation, the vial tray 110 is placed in the device and positionedproperly using the alignment tabs 106, 107. One or more samplecontainers 70 such as vials are inserted into respective apertures 125a-125 n depending upon the number of samples to be filtered. The lid 150is then placed over the vial tray 110, thereby enclosing the vacuumchamber which includes the vial tray 110 and any vials containedtherein. One or more filter assemblies 10 are each placed in arespective aperture 146 a-146 n, again depending upon the number ofsamples to be filtered. The remaining apertures are sealed by ensuringthat the corresponding door 147 associated therewith is in the closedposition. When a filter assembly 10 is disposed in an aperture 146 and acorresponding vial is disposed in the vial tray 110, a portion of thestem 35 is nested within the vial (FIG. 13), thereby reducing oreliminating any cross-contamination between that filter assembly 10 anda different vial, and reducing or eliminating any fluid spillage duringtransfer from the filter assembly 10 to the vial. Sample is introducedinto each of the sample reservoirs 12. The connector 133 is attached toa vacuum source such as with a quick disconnect and suitable hosing, andthe vacuum source is turned on (e.g., 25 in Hg). The handle 260 isactuated, placing the manifold in fluid communication with the vacuum,which seals the lid 150 and the body 100 together. The vacuum drives thefiltration in each of the filtration assemblies 10 simultaneously and inparallel, and the sample from each filter assembly is driven through themembrane, into and through the bore 36 of elongated tip 35, and directlyinto a corresponding unique vial with no cross-contamination. The vialsmay then be capped and removed from the tray, or may remain in the trayand the tray removed from the vacuum chamber and stored elsewhere, suchas under refrigeration. The filtered sample in the vials may undergofurther processing, such as liquid chromatography.

What is claimed is:
 1. A filter, comprising a sample reservoir definedby a fluid impervious wall, a membrane, a membrane support supportingsaid membrane and comprising concentric circumferential slits and aplurality of spokes which traverse said concentric circumferentialslits, and an axially disposed elongated member in fluid communicationwith said sample reservoir through said membrane, said elongated memberhaving a fluid outlet.
 2. The filter of claim 1, further comprising anaxially extending collar member adapted to seal said filter in afiltration device.
 3. The filter of claim 1, wherein said elongatedmember is in fluid communication with said sample reservoir via aclover-shaped aperture.
 4. The filter of claim 1, further comprising alower housing for said membrane support, wherein said sample reservoirincludes a base having an underside, and wherein said lower housing andsaid underside of said base each include a raised annular ring to assistin bonding said lower housing to said base upon the application of heat.5. A plurality of interconnected filters, each filter comprising asample reservoir defined by a fluid impervious wall, a membrane, amembrane support supporting said membrane and comprising concentriccircumferential slits and a plurality of spokes which traverse saidconcentric circumferential slits, and an axially disposed elongatedmember in fluid communication with said sample reservoir through saidmembrane, said elongated member having a fluid outlet; wherein saidfilters are interconnected with a connecting member comprising aplurality of annular rings.
 6. The plurality of filters of claim 5,wherein each annular ring of said plurality of rings is removablyaffixed to an adjacent annular ring.
 7. The plurality of filters ofclaim 5, wherein said elongated member is in fluid communication withsaid sample reservoir via a clover-shaped aperture.